Mount an USB connected Android based smartphone into Linux
User-mountable and world-readable, using fuse and jmtpfs:
Install required software:
$ apt-get install fuse jmtpfs usbutils
Connect the smartphone with an USB data cable and read out required information:
$ lsusb
The command returns a list of all connected USB devices; the line for my Moto G4 play looks like this:
Bus 001 Device 003: ID 22b8:2e82 Motorola PCS
Now use the printed Vendor and Product ID (before resp. after the colon) to create the according udev rule:
$ echo 'SUBSYSTEM=="usb", ATTR{idVendor}=="22b8", ATTR{idProduct}=="2e82", SYMLINK+="libmtp-%k", MODE="660", GROUP="audio", ENV{ID_MTP_DEVICE}="1", ENV{ID_MEDIA_PLAYER}="1"' >> /etc/udev/rules.d/55-android.rules
Create mountpoint, make sure that you are in the audio group and test setup:
$ mkdir /media/motomobil
$ chmod a+rwx /media/motomobil/
$ jmtpfs -o allow_other /media/motomobil/
$ fusermount -u /media/motomobil/
jmtpfs will grab the first available device. Allternatively, the device can be specified with the -device=<busLocation>,<devNum> switch, to dump the parameters, run jmtpfs --listDevices.
Add fstab entry:
$ echo "jmtpfs /media/motomobil fuse noauto,nodev,allow_others,rw,user,noatime 0 0" >> /etc/fstab
Burning a mixed-mode CD-R
It is possible to "enhance" an audio CD with arbitrary files as a bonus track. The following post shows how to create such a mixed-mode CD or enhanced CD on the command line.
Create suitable wav files with libav-tools
$ cd $AUDIOSOURCEDIR
$ for i in $(ls); do avconv -i $i /path/to/outdir/$i.wav; done
Note: ffmpeg will work as well, with the same syntax and options: just /avconv/ffmpeg/.
Burn the audio-tracks
$ cd $WAVDIR
$ wodim -v dev=/dev/sr0 speed=4 -multi -audio *.wav
The -multi switch (for multi session) is necessary to prevent wodim from closing the disk after burning. Additionally, I use the slow speed=4 option to burn sharper delimited dots and thus enhance the disk's readability in older (or dusty) audio players.
Analyze the audio-session and prepare the "bonus track"
$ TRACKINFO=`cdrecord -msinfo dev=1,0,0`
$ echo $TRACKINFO
0,105248
In this case, the first session started at sector 0 and the following will start at sector 105248. This information can now be passed to mkisofs or the newer xorrisofs:
$ xorrisofs -J -r -C $TRACKINFO -V $16_CHAR_DISKLABEL -o /path/to/data.iso /path/to/data
Append the iso to the disk
$ wodim -v dev=/dev/sr0 -data /path/to/data.iso
The resulting CD will serve the first session to all common audio CD players, while the second (data) session can be accessed with a CD-ROM drive.
Note: Not all CD-ROM drives support mixed-mode media - some may fail to access the audio tracks from the first session.
CLI Wifi setup with iw
This is a quick overview of the necessary commands and configuration to connect to wireless networks from the command line with iw and wpa_supplicant.
Preparation
Identify available Wifi adapters:
$ iw dev
Check the device status (from now on using device wlan0):
$ ip link show wlan0
Bring up the interface and scan for available networks:
$ ip link set wlan0 up
$ iw wlan0 scan
Now there are several possibilities to actually connect to the targeted wireless network:
Solution 1 - manually with wpa_supplicant and dhclient
Generate the wpa_supplicant configuration file (replace $SSID with the network's SSID, hit return and enter the passphrase):
$ wpa_passphrase $SSID >> /etc/wpa_supplicant.conf
Note: You might want to remove the (commented out) clear text passphrase from the resulting wpa_supplicant.conf file.
Connect to the wireless network and obtain an IP address:
$ wpa_supplicant -B -D wext -i wlan0 -c /etc/wpa_supplicant.conf
$ dhclient wlan0
Solution 2 - using wpa_supplicant with ifup/down
Add the Wifi configuration to your /etc/network/interfaces (of course $SSID and $PASSPHRASE have to be replaced by the actual values):
### File: /etc/network/interfaces
auto wlan0
iface wlan0 inet dhcp
wpa-ssid $SSID
wpa-psk $PASSPHRASE
To avoid the clear text passphrase in your interfaces file, you can run
$ wpa_passphrase $SSID
As before, you'll have to replace $SSID with the network's real SSID, hit return and enter the passphrase. When done, replace the $PASSPHRASE in the above /etc/network/interfaces file with the resulting 256bit value of psk.
Now bring up the interface, connect to the wireless network and obtain an IP address as usual with
$ ifup wlan0
Note: This solution will (try to) automatically connect to the configured wireless network when the system boots.
Checking the link
Finally, use ip or ifconfig to check the link status and ping a known host to verify connectivity:
$ ip addr show wlan0
$ ifconfig wlan0
$ ping -c 2 devuan.org
Mount a partition of a qcow2 (or raw) disk image
There are situations when you need to access a VM's disk / partition directly, e.g to reset a forgotten root password. For QEMU's qcow2 partitions this can be achieved with the "network block device" (nbd) driver and qemu-nbd from the qemu-utils package. (For "raw" disk images, see below.)
First, load the nbd kernel module:
$ modprobe nbd max_part=12
Now use the command qemu-nbd to make the disk image available as network block device:
$ qemu-nbd --connect=/dev/nbd0 /path/to/image.qcow2
fdisk can be used to list the available partitions inside the disk image:
$ fdisk -l /dev/nbd0
Finally mount the partition (in this case partition #2) to an arbitrary mount point:
$ mount /dev/nbd0p2 /path/to/mountpoint/
chroot into the directory as usual. When you're done, exit the chroot, then unmount the partition and disconnect the network block device:
$ umount /dev/nbd0p2
$ qemu-nbd --disconnect /dev/nbd0
Similarly, a partition inside a raw disk image can be mounted as loop device:
$ losetup /dev/loop0 /path/to/diskimage.img
Make the partition mappings available:
$ kpartx -av /dev/loop0
And mount the partition (here partition #1):
$ mount /dev/mapper/loop0p1 /mnt/image
Alternatively, the partition can be mounted directly: In this case its offset (in bytes) from the beginning of the disk image needs to be passed to the mount command, fdisk will provide the necessary values to calculate it.
Here an example disk image with only one partition:
$ fdisk -l netinst.img
Disk netinst.img: 32 MiB, 33554432 bytes, 65536 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0xb6bdaf05
Device Boot Start End Sectors Size Id Type
netinst.img1 * 2048 65535 63488 31M b W95 FAT32
The "Start" sector of the target partition (here 2048) needs to be multiplied with the disk's sector size, here 512 bytes. In this case the partition's offset is 512*2048=1048576 bytes:
$ mount -o loop,offset=1048576 netinst.img /path/to/mountpoint/